Leicester allen



(No Model.)

L. ALLEN.

PROCESS OF AND APPARATUS FOR DYNAMIC 000mm}.

No. 252,921. Patented Jan. 31,1882

a zz ma/a UNITED STATES PATENT OFFICE.

LEICESTER ALLEN, OF NEW YORK, N. Y., ASSIGNOE TO HENRY T. BROWN, TRUSTEE, OF SAME PLACE.

PROCESS OF AND APPARATUS FOR DYNAMIC COOLING.

SPECIFICATION forming part of Letters Patent No. 252,921, dated January 31, 1882.

Application filed May 25, 1881. (No model.)

To all whom it may concern:

Be it known that I, LEICESTER ALLEN, of the city, county, and State of New York, have invented Improvements in Processes of and Apparatus for Dynamic Cooling; and 'I hereby declare the following to be a full, clear, and ex- Iaet description of the same, reference being bad to the accompanying drawing, forming a part of this specification.

My invention relatesto that class of refrigerating processes and apparatus in which a volume of gas is first compressed; the temperature of the so compressed gas is then reduced to or toward, that of the gas before its compression; third, the gaseous body is expanded in the performance of outer work, and, lastly, the air so expanded and which has become cooled by the performance of work during the process of expansion is restored to its original volume or approximated toward such volume by-absorption of heat from some substance or inclosure which is thereby refrigerate For various reasons air is the most desirable gas for effecting this kind of cooling; but in the simple method of alternately compressing and expanding it, described above, and commonly known as the Carnot cycle, it has the disadvantage that alarge volume must be operated upon to gain a notable effect, thus necessitat- 0 ing a large machine. The total losses of effect, commonly called passive resistances, are therefore much larger than would be the case could a gas of greater specitic heat per volume be employed. i

The purpose of this my invention is to reduce theproportion ofthese passive resistances as compared with the total cooling effect pro duced, or as compared with the mechanical power expended in gaining a stated cooling 4o effect, and also to enable machines designed to carry out the Carnot cycle to be made much lighter and smaller in proportion to their cooling capacity than has hitherto born the case.

The first part of my inventionconsists in 4 5 first compressing a gaseous body from ordinary atmospheric pressure to a stated higher pressure in any suitable reservoir or receptacle,where it is then allowed to assume the ordinary temperature of the surrounding medium; second, in compressing this already compressed gas to a higher pressure, cooling it at such higher pressure to extract the heat equivalent of the work expended in such compression, and then expanding it in the performance of outer work down to the aforesaid stated pressure in said reservoir, then restoring to it as nearly as practicable the temperature at which it was taken from the reservoir by heat taken from the inclosure or substance to be cooled, repeating this process till the required refrigeration is 6o attained, the gas operated upon not being allowed to resume its ordinary atmospheric pressure, but being only expanded down to the stated pressure in said reservoir, or as nearly to such pressure (more or less) as it is practicable to maintain it;

The leakage from the system is supplied by a small auxiliary air-pump in order to main tain the pressure of the gas in said reservoir at its stated maximum, or as nearly thereto as practicable, and the difference between the amount of power required to perform the compression and overcome the passive resistances and the power derivable from the expansion of the air is supplied by a steam-engine or other 5 motor; and the combination of the steam-engine or othermotor,air-engine,air-compressor, intermediate cooler, and auxiliary pump for supplying amount of air lost by leakages, all arranged and operating substantially as herein described, also constitutes a part of my invention. Both the work of compression and the outer work performed by the expansion will be greater in proportion as the weight of air or other gaspassed through thecycle is greater, and this weight will be greater for any given volume when the air or other gas is compressed to and notpermitted to fall below a stated pressure higher than ordinary. Thus a cubic foot of air which has been compressed to four 0 atmospheres will weigh as much as four,feet of air at the same temperature and at a pressure of only one atmosphere; and if this foot of air be com pressed from four to eight atmospheres as much work will be required to per- 5 form the compression as would be required to compress four cubic feet having the same initial temperature from a pressure of one atmosphere to two atmospheres. Conversely, in expanding the air again from eight atmospheres roo to four atmospheres pressure, the cubic foot of air would develop by its expansion as much mechanical power as would be attainable from the expansion of four cubic feet of air having the same initial temperature from two atmospheres down to one atmosphere. As the cooling efl'ect is exactly proportional to the outer work performed by the expansion of the air, it follows that the expansion of one cubic foot of air from eight down to four atmospheres will produce the same cooling efl'ect as the expansion of four cubic feet from two atmospheres down to one atmosphere; but to expand the one cubic foot of air from eight atmospheres down to four atmospheres in an engine will require a cylinder only about one-fourth as large as would be requisite to expand four cubic feet of air from two atmospheres down to one atmosphere, the final volumes reached after the initial temperatures are restored in the two cases being respectively two cubic feet and eight cubic feet. A similar reduction of size is also rendered possible in the compressorcylinders.

To carry out my invention the apparatus shown in the drawing, or an equivalent apparatus, is employed.

Referring to the drawing, A represents a steam-engine; B, an air-compressor; G, a cooler; D, an air-engine; E, asurlace-cooler for the reception of the expanded air and the substance to be cooled. (In this example a liquid is to be cooled.) F F F F F" are pipes for connecting the elements ofv the system. H H Ii. H H are stop-cocks in said pipes for controlling the flow of the gas in charging and working the machine; and I, a smaller auxiliary air-pump, which takes its air from the outside atmosphere and injects the same into the machine (shown as delivering-cooler E) to compensate for the leakages. The pump I may be driven by,direct connection with the piston of the compressor O, or in any other suitable manner.

The whole forms (as nearly as practicable) a closed cycle. The compressor B takes its air from the surface-cooler E, the cooler 0 takes its air from the compressor B, the air-engine D takes its air from the cooler O, and the surface-cooler E receives the air from the air-engine D. The cooler E is the representative of any refrigerating-inclosure, whether it be used to cool liquids or not, the cold air passing through a tube, box, passage, or other device for taking heat from the outside air or other substance surrounding it.

The two engines and the compressor are represented as connected to a single-crank shaft and workingsynchronously; butotherarrangements of the engines and compressor are possible.

It is hardly necessary to mention that any other motor may be substituted for the steamengine A.

What I claim as my invention, and desire to secure by Letters Patent, its- 1. In a process for dynamic cooling, wherein air or other gas is firstcompressed, then cooled, then expanded to perform outer work, the

mode of increasing the coolin getl'ect ofa statedbulk or volume of air or other gas, which consists in condensing the gas to and maintaining it above a stated limit materially higher than the normal atmospheric pressure, substantially as and for the purpose set forth.

2. In a process for dynamic cooling, wherein air or other gas is first compressed, then cooled, and then expanded in the performance of outer work, the mode of beginning and ending the cycle at a stated pressure materially above the normal atmospheric pressure, substantially as herein described.

3. In a dynamic cooling apparatus in which air or other gas is first compressed, then cooled, then expanded in the performance of outer work in a closed cycle to compress air above and expand it again to a minimum limit of pressure materially higher than the normal atmospheric pressure, substantially as herein described, the combination, with a steam-engine or other prime motor, air-engine, air-compressor, and intermediate coolers, of an auxiliary pump for taking air from the exterior atmosphere and injecting it into the system in sufficient quantities to compensate for leakages, substantially as herein described and specified. V

LEICESTER ALLEN.

Witnesses:

FREDK. HAYNES, Tnoarns E. Brnorr. 

